XK X251 whirlwind (in construction)

EDIT: BE AWARE, XK INTRODUCED RECENTLY A NEW VARIANT OF THE FC: NO MORE ACRO BUT RATITUDE MODE INSTEAD. IT'S MORE EASIER FOR BEGINNER BUT LESS FOR ADVANCED FPV PILOTS. THEY ALSO REPLACED CARBON LEGS BY PLASTIC ONES.

EDIT 2 (07/24/16): BE AWARE, REAR SCEWS HOLDING THE LANDING GEAR BRACKETS ARE TOO LONG AND CAN DAMAGE TWO FETS OF THE ESC BOARD AS DEPICTED BELOW.

PLEASE REDUCE THEIR LENGTH FOR SAFETY

INTRODUCTION

Clearly since few months, we can see more and more cheap toy-quadcopter directly equiped of a brushless setup, of course thanks to some 4-in-1 cheaper ESC boards. After the very sporty JJRC X1, here is the XK X251 Whirlwind also sold around 125 USD. WIth the X251, a real "accro" flight mode is available and thanks to the presence of the Futaba radio protocol, we can expect great control range as well.

A 2S 950mAh LiPo with 25C as discharge rate... so pretty good. Unfortunatly, no main lead connectors installed. It means, you can really use
a professional charger and be forced to employ the provided one. With it, 2 hours are required to charge the LiPo (the red led should be turn off
when the battery is charged)

An alternative model can be installed, the turnigy nanotech 950mAH with JST connector

No problem to split in two the canopy after the 5min unscrewing session (13 screws to remove)

The blue RF daughter board is installed on top. Here, we can find the CC2500 RF chip associated with the Futaba S-FHSS protocol.
In bottom right location, the invensense MPU6050C for the 6-axis stabilization. No USB slot for a direct software connexion but a free UART port is here.

The micro contact button is the bind button

Some of the FET populating the 4-in-1 ESC board

Transmitter

The X7 radio uses a deluxe and large chassis.

Versus the XK X350 radio, notice the presence of this red toggle button associated with the camera recording.
The right switches are the throttle hold (safety switch cutting immediatly motors) and the dual rate respectively. The left switches
are the 3D/6G and stabilized/accro ones respectively. If you turn on the accro mode, the main difference between the 3D/6G will be about maximum pitch&roll rates. In 3D of course, you can perform easy manual flips.

The top left switch is actually useless (but can be used) since no real 3D/inverted capacity

and super crash resistant .... Ok Ok maybe I regret the absence of colored props and a strong front LEDs to keep orientation.

CONCLUSIONS

If you are looking for a first brushless & cheap machine robust, fast, agile, able to carry a small möbius or FPV kit and with a great radio range.... you can't be wrong with the XK X251... For me it's almost the perfect machine. The 6G mode is ideal for beginners very stable. Later the 3D/accro mode will let you to fly in real racer conditions especially equiped with the 5.8G FPV kit. The XK X251 is for me better than the JJRC in a lot of points: better and programmable radio, better lights, better radio range, real accro/3D mode available, more solid and lighter.. What else ? The XK X251 won my SebyAward Q1 2016.

- No power switch
- No arming/disarming sequence (potentially dangerous)
- No front LED (to help to keep orientation)
- M4 prop cap
- No lead connector for the LiPo- No programmable settings X6/X7 have 10 memory banks

I think the lack of disarming comes from the helicopters, where it's common to just switch on the throttle hold switch when powering on the heli. All this throttle up, than down, or other stick combos to arm the motors, that are common on (RTF) quads, are left out.

I agree it's something to be aware of, but coming from helicopters into the quad world, seeing other methods instead of throttle hold, was actually feeling weird, and needed getting used to.

I think the lack of disarming comes from the helicopters, where it's common to just switch on the throttle hold switch when powering on the heli. All this throttle up, than down, or other stick combos to arm the motors, that are common on (RTF) quads, are left out.

I agree it's something to be aware of, but coming from helicopters into the quad world, seeing other methods instead of throttle hold, was actually feeling weird, and needed getting used to.

Yes, as you already knows, the X7 radio is used for both helicopters and quads...

Really I got very positive impression with this X251....

PS. Sorry, the web sever hosting my photos is down for at least the next 10-12h

Yes, as you already knows, the X7 radio is used for both helicopters and quads...

Really I got very positive impression with this X251....

PS. Sorry, the web sever hosting my photos is down for at least the next 10-12h

How about uploading the photos to a blog topic on your personal page on RCG? Would also make the pictures load a lot faster. Each of your topics that has a lot of photos, often takes 10 seconds or more to load

How about uploading the photos to a blog topic on your personal page on RCG? Would also make the pictures load a lot faster. Each of your topics that has a lot of photos, often takes 10 seconds or more to load

I think they are trying to run out all their stocks with the current promotional price of USD 85. Should there be any remaining ones after the XK X251/252 is launched then it shall be priced even lower. Even more so if the XK X251/252 could draw up an early bird sale price of USD 100 that will definitely shake them up.

A 2S 950mAh LiPo with 25C as discharge rate... so pretty good. Unfortunatly, no main lead connectors installed. It means, you can really use
a professional charger and be forced to employ the provided one. With it, 2 hours are required to charge the LiPo (the red led should be turn off
when the battery is charged)

You can split the balance connector in a balance and charge lead. All you need is a 2S extension wire, cut the red and black wires, and connect a wire with a plug that is compatible with your charger, red to red, black to black. When a LiPo has seperate discharge leads and balance leads, underneath the shrink wrap the same connections are made. Red to pos, black to minus, and middle balance wire between where pos of one cell connects to neg of the other cell of the 2S pack.

You can split the balance connector in a balance and charge lead. All you need is a 2S extension wire, cut the red and black wires, and connect a wire with a plug that is compatible with your charger, red to red, black to black. When a LiPo has seperate discharge leads and balance leads, underneath the shrink wrap the same connections are made. Red to pos, black to minus, and middle balance wire between where pos of one cell connects to neg of the other cell of the 2S pack.

Yes for sure by modding the LiPo... What I mean here, I regret the non-presence of the main lead connectors.... Ultra beginners won't do the battery mod and will buy official spare....